Resistive memory devices store information by controlling the resistance across each memory cell such that a read current through the memory cell in the memory device will result in a voltage drop having a magnitude that is based on the information stored in the memory cell. For example, in certain magnetic memory devices, the voltage drop across a magnetic tunnel junction (MTJ) in each memory cell can be varied based on the relative magnetic states of the magnetoresistive layers within the memory cell. In such memory devices, there is typically a portion of the memory cell that has a fixed magnetic state and another portion that has a free magnetic state that is controlled to be either parallel or antiparallel to the fixed magnetic state. Because the resistance through the memory cell changes based on whether the free portion is parallel or antiparallel to the fixed portion, information can be stored by setting the orientation of the free portion. The information is later retrieved by sensing the orientation of the free portion. Such magnetic memory devices are well known in the art.
Memory devices, including magnetic memory devices, may be used in applications in which tampering is a concern. For example, magnetic memory devices may be used in smart meters or gaming applications. In such applications, a user may attempt to tamper with the data stored within the memory device by applying an external magnetic field or other external stimulus in an attempt to modify the information stored within the memory device.
Therefore, it is desirable to provide techniques for detecting such tampering attempts as well as responsive measures to help preserve the viability of such memory devices in various applications in which tampering is a concern.